The deployment of advanced high bit-rate mobile networks has opened up new opportunities for delivering services in a way that was not possible with earlier, second generation, wireless networks. Third generation systems such as Universal Mobile Telephone Service (UMTS) will enable the delivery of new digital services such as video calls and the playback of multimedia applications that are comprised of audio and video clips. This may also be enabled by lower bit-rate systems such as High Speed Circuit Switched Data (HSCSD) and General Packet Radio Service (GPRS) specified for use with the Global System for Mobile Communications (GSM) wireless standard.
Although the high bit-rates of UMTS systems are promising for the provision of digital services, many estimates forecast that these systems can reliably deliver data rates of only 64 to 384 kbit/s to moving mobile terminals, as opposed to up to 2 Mbit/s for stationary environments. The moving terminal rates provide fairly good performance for delivering high quality digital audio and acceptable quality moving image clips. However, at these transfer rates, it will be difficult to handle very highly data-intensive tasks such as delivering high quality full-motion video and transferring very large data files to mobile terminals. Attempts at downloading very large data files is likely to lead to inconveniently long downloading times, and is unlikely to be the most economical in terms of cost per megabyte. Accordingly, alternative broadband delivery channels that could provide a practical solution for highly data-intensive tasks in terms of lower cost and convenience for the parties involved have been investigated.
One such delivery channel that has shown promise is Digital Video Broadcasting (DVB). DVB-T, which is related to DVB-C (cable) and DVB-S (satellite), is the terrestrial variant of the DVB standard and is a wireless point-to-multipoint data delivery mechanism developed for digital TV broadcasting and based on the Moving Picture Experts Group(MPEG)-2 transport stream for the transmission of video and synchronized audio. DVB-T has the capability of efficiently transmitting large amounts of data over a radio channel to a high number of users at a low cost (the cost being low when compared to data transmission through mobile telecommunication networks using e.g. UMTS/GPRS). DVB-T data rates have been shown to provide up to 4-20 Mbit/s, where the lower end of the range corresponds to reception within a very high speed (300 km/h) moving receiver. Another advantage of DVB-T is that it has proven to be exceptionally robust, particularly in that it works well with receivers moving in geographic conditions that would normally affect other types of transmissions, such as with the rapid changes of reception conditions found when moving in hilly or mountainous terrain.
Other examples of broadband data broadcast networks include that provided under the Advanced Television Systems Committee (ATSC). Both ATSC and DVB utilize a containerisation technique in which content for transmission is placed into MPEG-2 packets which act as data containers. Thus, the containers can be utilized to transport any suitably digitised data including, but not limited to High Definition TV, multiple channel Standard definition TV (PAL/NTSC or SECAM), and broadband multimedia data and interactive services.
The combined use of mobile telecommunications with a broadband delivery channel such as DVB-T has been proposed in the past in order to achieve efficient delivery of digital services to users on the move. This would take advantage of existing infrastructures in the effort to provide personal communications (already prevalent) and the growing demand for Internet access, together with the expected rise of digital broadcasting, so that users can receive these services with a single device. Furthermore, DVB-T is a cross-platform standard that is shared by many countries thereby avoiding many issues caused by frequency compatibility and roaming. The combination of mobile telecommunications and a relatively very low cost digital broadband channel provides the possibility of interactive services including uni-directional and bi-directional services such as audio and video streaming (TV & Radio), file downloads and advanced gaming applications etc. This allows some flexibility in the way different media content is combined, delivered and consumed.
Because of the nature of the crossmedia delivery, different content formats from one content provider could easily be unidentifiable by the end user, which reduces the motivation of an individual content provider to provide content to content aggregators or service providers.